Since this swap was based on book "Harry Potter and the Order of the Phoenix," I made up my mind to have the book shaped like Grimmauld Place.
Before opening the book, you have to open an envelope attached which reads :
Inside is the first artist trading card. . .
The back of the card:
So once you read it, open the book, and as in the novel, there magically appears Number 12 Grimmauld Place.